PWM problem in LPC1227 with PIO1_6

r_michalek — Sun, 23 Jan 2022 19:06:49 GMT

Hello,

I am trying to use PIO1_5 and PIO1_6 for PWM. PWM works on the PIO1_5 without problems, but not on the PIO1_6. When I set PIO1_6 as CT16B1_MAT1, there is always a log.0, even if EM1 bit changes in the EMR register. This situation executing code with MY_SWITCH = 1.

I have tried to use PIO1_6 as a GPIO pin in order to check if this pin is ok (toggling). It is definitely working properly. Also I changed PIO1_6 to PIO0_16 with CT16B1_MAT1 mode and it works perfectly. This situation executing code with MY_SWITCH = 2.

I tested on two HW - the original LPCXpresso1200 with LPC1227 in LQFP64 case and one on my boards with LPC1227 in LQFP48. Same behaviour on both chips.

Here is the code:

/* =============================================================================== Name : Test_PWM.c Author : R-Michalek Version : Copyright : $(copyright) Description : Simple test of PWM on PIO1_5 and PIO1_6 =============================================================================== */ //#ifdef __USE_CMSIS #include "LPC122x.h" //#endif #include <cr_section_macros.h> /* * MY_SWITCH * = 1 ~ PWM on PIO1_5 and PIO1_6 - wanted version * = 2 ~ PWM on PIO1_6 and PIO0_16; PIO1_6 is on GPIO mode and toggles in main loop */ #define MY_SWITCH 1 #define IOCON_FUNC_0 (0) #define IOCON_FUNC_1 (1) #define IOCON_FUNC_2 (2) #define IOCON_FUNC_3 (3) #define IOCON_FUNC_4 (4) #define IOCON_MODE_PULL_UP (1 << 4) #define IOCON_ADMODE_DIGITAL (1 << 7) int main(void) { volatile unsigned char i = 0; LPC_SYSCON->SYSAHBCLKCTRL = 0x0001001FUL; // Enable SYS, ROM, RAM, FLASHREG, FLASHARRAY and IOCON LPC_SYSCON->SYSAHBCLKCTRL |= (0x01 << 8); // Enable CT16B1 LPC_SYSCON->SYSAHBCLKCTRL |= (0x01 << 30); // Enable GPIO1 LPC_SYSCON->SYSAHBCLKCTRL |= (0x01 << 31); // Enable GPIO0 #if MY_SWITCH == 1 LPC_IOCON->PIO1_5 = IOCON_FUNC_3 + IOCON_ADMODE_DIGITAL; // CT16B1_MAT0 LPC_IOCON->PIO1_6 = IOCON_FUNC_3 + IOCON_ADMODE_DIGITAL; // CT16B1_MAT1 #endif #if MY_SWITCH == 2 LPC_IOCON->PIO1_5 = IOCON_FUNC_3 + IOCON_ADMODE_DIGITAL; // CT16B1_MAT0 LPC_IOCON->PIO0_16 = IOCON_FUNC_4 + IOCON_ADMODE_DIGITAL; // CT16B1_MAT1 LPC_IOCON->PIO1_6 = IOCON_FUNC_0 + IOCON_ADMODE_DIGITAL; // GPIO LPC_GPIO1->DIR |= (1 << 6); // GPIO Output #endif // configure CT16B1 LPC_CT16B1->TCR = 0x02; // reset on LPC_CT16B1->TCR = 0x00; // reset off LPC_CT16B1->CTCR = 0x00; // Timer mode LPC_CT16B1->PR = 0x0000; // no pre-scale LPC_CT16B1->MR0 = 250; // PWM on MAT0 (ratio 1:1) LPC_CT16B1->MR1 = 250; // PWM on MAT1 (ratio 1:1) LPC_CT16B1->MR2 = 500; // cycle length LPC_CT16B1->MCR = (0x01 << 7); // reset on MR2 => cycle length LPC_CT16B1->CCR = 0x00; // disable all captures LPC_CT16B1->PWMC = 0x03; // MAT0 and MAT1 is enabled for PWM mode LPC_CT16B1->EMR = (0x02 << 4) | (0x02 << 6); // set bit EM0 and EM1 to high on match LPC_CT16B1->TCR = 0x01; // counter enable // end of configuration while (1) { i = 1 - i; #if MY_SWITCH == 2 // SetGPIO1(PIO1_6, i); i ? (LPC_GPIO1->SET = 1<<6) : (LPC_GPIO1->CLR = 1<<6); #endif // "Dummy" NOP to allow source level single // stepping of tight while() loop __asm volatile ("nop"); } return 0 ; }

Re: PWM problem in LPC1227 with PIO1_6

xiangjun_rong — Mon, 24 Jan 2022 02:01:44 GMT

Hi, Rastilav,

Pls refer to the pin assignment, for the P1_6 pin, it appears that you should set the FUNC as 2, but you set it as 3.

Pls use the line

LPC_IOCON->PIO1_6 = IOCON_FUNC_2 + IOCON_ADMODE_DIGITAL; // CT16B1_MAT1

The following is your original code:

LPC_IOCON->PIO1_6 = IOCON_FUNC_3 + IOCON_ADMODE_DIGITAL; // CT16B1_MAT1

Hope it can help you

XiangJun Rong

Re: PWM problem in LPC1227 with PIO1_6

r_michalek — Mon, 24 Jan 2022 06:43:21 GMT

Oh, I was blind. I checked it several times and still didn't see it. Thank you.

topic PWM problem in LPC1227 with PIO1_6 in LPC Microcontrollers

PWM problem in LPC1227 with PIO1_6

Re: PWM problem in LPC1227 with PIO1_6

Re: PWM problem in LPC1227 with PIO1_6